In order to electrically connect a conductive object such as an antenna to a conductive pattern of a printed circuit board or to electrically connect to the ground for eliminating static electricity or electromagnetic interference (EMI), there is provided an elastic connecting terminal mounted on a conductive pattern of a printed circuit board by soldering.
In case that the electric connecting terminal is used for connecting electricity in up and down directions so as to compensate for a vertical dimensional tolerance between a printed circuit board and a conductive object which will be electrically connected, the electric connecting terminal needs to have a longer operating distance in up and down directions and needs to be made from a predetermined material in a structure in which a soldering mounting may be available by a surface-mount method for mass production.
For example, if a mechanical tolerance between the printed circuit board and the conductive object becomes larger, a longer operating distance of the electric connecting terminal is necessary so as to electrically connect the printed circuit board to the conductive object.
As disclosed in the Korean Utility Model Registration No. 332757 invented by the same applicant, there is provided a conductive gasket in which each of metallic sheets is made as a cylinder of which one side is closed and the other side is open, and the other sides of the cylinders which are open are slidably inserted into each other, and a metallic spring is inserted inside in such a way that the metallic spring is not disengaged.
However, since it does not need to fix such a metallic spring to a metallic sheet such that the metallic spring is temporarily fixed so as to keep the metallic spring before a reflow process or such that the metallic spring is maintained in a simple inserted state, a vacuum pickup process may be hard for the sake of surface-mounting work.
The top cylinder may be disengaged and taken off by blowing hot air when reflow-soldering the bottom cylinder onto the printed circuit board because the metallic sheet and the metallic spring are not surely coupled to each other.
In addition, the top cylinder may be disengaged and taken off by recovery force of the spring when the objects move during the use of the gasket.
Since there is not any assistant portion to hold the spring in place within the top and bottom cylinders, the inner spring may be distorted during compression.
In the related art, there is a pogo pin which is widely used when electrically inspecting a printed circuit board or a semiconductor chip or which is used in medical equipment, more specifically, in obesity or skin treatment equipment. The photos illustrated in FIG. 1A is an example to which the pogo pin is adapted.
Referring to FIG. 1B which illustrates a schematic structure of a pogo pin, a plunger 60 is inserted in a case 50 with a spring 70 inserted therebetween and elastically moves in up and down directions.
Here, the pogo pin has a predetermined height of about 3 mm or more, which however entails increasing the height of the fixed member so as to obtain enough operating distance in up and down directions because a guide portion 64 of the plunger 60 inserted in the case 50 should be longer so as to balance the relatively large plunger 60 as illustrated in FIG. 1B. In this reason, it is hard to economically manufacture the products whose heights are about 2 mm or more and operating distances are longer.
The above-described problems occur because it was not considered to independently solder the pogo pin onto the printed circuit board at initial stages. The pogo pin is generally used in a state where the pogo is assembled to a mold.
For this reason, it is hard to provide a pogo pin which has a low height and a long operating distance in up and down directions, and it is hard to mount the pogo pin onto a printed circuit board using a reel tape through a reflow soldering process using vacuum pickup and solder cream.
Since a top surface 62 of the plunger 60 of the pogo pin is formed in a dome shape, the vacuum pickup for surface-mounting is performed hard.
Since the plunger 60 of the pogo pin is manufactured by cutting a typical metal, manufacturing costs is a lot, and there is a limit in making the plunger 60 thinner.
Since the plunger 60 manufactured by cutting metal is heavier than the case 50, the center of gravity may lean in an upward direction, which causes more movement (swaying) by hot air during the reflow soldering process.